The present invention relates to x-ray detectors and, more particularly, to a novel solid state x-ray detector having shaped collimator plates for substantially reducing the intensity of the x-ray flux falling on edges of a misaligned x-ray detector element.
Known x-radiation measurement apparatus, such as that utilized for computerized tomography and the like, requires measurement of x-ray flux with a high precision; generally x-ray flux measurement error of less than 0.1% is highly desirable. Many x-ray systems utilize more than one detector element; in particular, most computerized tomography systems require a multiplicity of detector elements which simultaneously receive and measure the x-ray flux. As poly-energetic x-ray sources are usually utilized to minimize the x-ray exposure time of the patient, each of the multiplicity of detector elements must respond to an x-ray signal of both widely varying intensity and variable x-ray spectrum and must so respond in a manner nearly identical to the response of all other detector elements in the detection system.
Many computerized tomography systems utilize an array of scintillating elements receiving the x-ray flux and converting the flux to quanta of photons at longer wavelength, typically in the ultraviolet and/or optical wavelengths; and a collimator, i.e. a means for limiting the angle over which the x-ray flux can enter the scintillator. In scintillating element detectors of the type having a rectangular parallelpiped scintillator bar, the detector response with respect to the incident x-ray energy depends upon the deviation of the scintillator from a perfect rectangular parallelpiped, and typically requires deviations of less than one part in a thousand. The detector response also depends, to some degree, upon the scattering of incident x-rays from any collimating means onto the scintillator element. It is desirable to have an x-ray detector wherein collimator scattering is reduced and the dependence upon deviation from a perfect rectangular parallelpiped shape of the scintillator element is decreased, to reduce manufacturing costs and increase mamufacturing yield.